object cache: init entry lock

This entry lock initilization was carelessly dropped while splitting the
'optimize push' patch.

Signed-off-by: Liu Yuan <tailai.ly@taobao.com>
Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
collie: use SD_OP_DELETE_CACHE to delete cache

We'd better broadcast SD_OP_DELETE_CACHE to all the nodes that delete cache in
one shot to make sure the cache is completely removed on all nodes.

Signed-off-by: Liu Yuan <tailai.ly@taobao.com>
Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>